Software I: Utilities and Internals Documents

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Software I: Utilities and
Internals
Lecture 1 UNIX for Beginners
What is UNIX?
UNIX is a time-sharing operating system with userchosen shells (user interfaces) and one kernel
(operating system core, which allocates and control
resources such as CPU time,

Software I: Utilities and
Internals
Lecture 6 The Basics of Perl
Origins and Uses of Perl
Perl was developed in 1987 by Larry Wall. Its design
goal was to expand on the text-processing features of
awk.
The language has had many features added since
then

Software I: Utilities and
Internals
Lecture 5 Filters
What Are Filters?
A filter is a UNIX program that reads input (usually
stdin), performs some transformation on it and
writes it (usually to stdout).
This follows the UNIX/Linux model of building
simp

Software I: Utilities and
Internals
Lecture 4 Regular Expressions,
grep and sed
What Is A Regular Expression?
A regular expression is a pattern consisting of
a sequence of characters that is matched
against text.
Regular expressions give us a way of
rec

Software I: Utilities and
Internals
Lecture 3 File System Commands
The File System
A file in UNIX is a sequence of bytes. UNIX imposes no
structure in a file and there is no extension implicit in a file
name.
UNIX views peripheral devices as files:
[SIE

Software I: Utilities and
Internals
Lecture 7 Using The Shell
What is bash?
bash (Bourne Again Shell) is designed as a
free replacement of the Bourne shell (the
original UNIX shell) to be bundled with Linux.
It is freely available from the GNU project.

Software I: Utilities and
Internals
Lecture 8 Shell Programming Using
bash
Steps in Writing a Shell Script
The first line identifies the file as a bash
script.
#!/bin/bash
This is called the magic number; it identifies
theprogam that should interpret th

CSC 271 Software I: Utilities
and Internals
Lecture 13 : An Introduction to File
I/O in Linux
File Descriptors
All system calls for I/O operations refer to open
files using a file descriptor (a nonnegative
integer).
File descriptors are used to refer to

CSC 271 Software I: Utilities
and Internals
Lecture 12 : File Systems
The Concept of A File
A file is a collection of data stored on
external device
or
A file is a collection of data entering or
exiting the computer.
File Attributes
Files have various

CSC 271 Software I: Utilities
and Internals
Lecture 11 : Processes and
Programming
UNIX/Linux and Processes
In UNIX and Linux, everything is done
within the context of a process.
A terminal checking to see if someone is trying
to log in is a process.
L

CSC 271 Software I: Utilities
and Internals
Lecture 9 : What are Processes?
The Process Concept
Originally, computers ran only one program at a
time, which had total access to all of the
computers resources.
Modern systems run many programs concurrently

CSC 271 Software I: Utilities
and Internals
Lecture 10: An Introduction to
Operating Systems
What Is an Operating System?
An operating system is the software that
serves as an interface between the user (or
his/her software applications) and the
computer